/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.pulsar.reactive.client.api;

import org.apache.pulsar.client.api.Message;

/**
 * Function to group messages that will be processed by the same instance of concurrent
 * message handler.
 */
public interface MessageGroupingFunction {

	/**
	 * Resolves a processing group for a message. This is used for implementing
	 * key-ordered message processing with
	 * {@link ReactiveMessagePipelineBuilder.ConcurrentOneByOneMessagePipelineBuilder}
	 * @param message the Pulsar message
	 * @param numberOfGroups maximum number of groups
	 * @return processing group for the message, in the range of 0 to numberOfGroups,
	 * exclusive
	 */
	int resolveProcessingGroup(Message<?> message, int numberOfGroups);

}
